The present invention relates to a valve for controlling an opening for the passage of fluid into and out of a pressure accumulator. A valve member, which by the elastically expanding membrane of the pressure accumulator can be brought against the force of a spring to the closed position, is connected to a piston acted upon by part of the fluid passing through the valve housing, tending thereby to move the valve member to the open position.
In a known valve of this type, the valve member has at one end a plate-shaped portion adapted to cooperate with the valve seat and a stem portion projecting therefrom which is provided with a longitudinal bore leading to a space defined at one end by a piston fixedly connected to the valve stem. Below the plate-shaped portion of the valve member there are provided radial bores which communicate with the bore extending through the valve stem.
In valves of the aforementioned kind the problem exists that, when fluid passes at high speed out of the pressure accumulator, the valve will be prematurely closed due to the underpressure forming in the valve gap. Provision of a stronger spring biasing the valve to the open position is for various reasons not suitable.
In this known valve fluid will pass through the radial bores and the longitudinal bore into the space defined at one end by the piston, to thus form a counter force which is supposed to prevent a premature closing of the valve. It has however been established that this arrangement does not operate in a stable and secure manner due to the flow condition of the liquid below the valve seat.